From experience, it is known that the behaviour of a tennis player during a game of tennis is influenced at a rate of 70 to 80% by the type of stringing of the player's tennis racket. While it is true that the frame and the handle of a tennis racket are important too, it must be pointed out that the stringing elasticity of the tennis racket, which is individually matched to the respective tennis player, is of paramount importance for a successful result of the game. The individual racket stringing elasticity, matched to the respective player, can only be determined, if at all, after lengthy testing periods. This is added to the fact that the opinions existing with respect to the suitability of a hard or more elastic type of stringing of the tennis racket to guarantee a greater success of the game largely deviate from each other. Up to the present, no device is known that could give a useful and predictable indication in this respect. Consequently, when it comes to the choice of a specific stringing elasticity of a tennis racket head, there will be a conflict of goals between the possibility of achieving high ball speeds when using a rather soft, elastic type of racket stringing and the desired increased ball control when using a harder stringing type.